Various techniques have been proposed for reducing the degrading impact of image artifacts on cardiac MRI studies. For example, U.S. Patent Application Publication 2009/0275822 describes a series of MR image frames that depict a subject's heart at successive cardiac phases. Delayed enhancement of infarcted myocardium is depicted in some of the image frames by administering a contrast agent prior to data acquisition. Data acquisition is performed in a single breath hold. The acquired MR image frames depict contrast between blood, viable myocardium and nonviable myocardium, and they depict left ventricle wall thickness and wall thickening throughout the cardiac cycle. In an embodiment, a scatter plot, which has the T1* versus steady state value of every image frame pixel is fed into a fuzzy clustering process and the pixels are automatically separated into three clusters. The pixels can then be color coded on a displayed image frame according to the tissue type which it has been classified-infarcted myocardium, normal myocardium or blood. From the probability values produced by the fuzzy clustering process it is also possible to segment pixels made up of a mixture of infarcted myocardium and normal myocardium. The number of pixels in this resulting “gray zone” indicated by this mixture of two tissue types has been shown to predict which subjects are more likely to suffer cardiac arrhythmias.
As another example, U.S. Patent Application Publication 2015/0192653 describes systems and methods for cardiac MRI that allow for continuous un-interrupted acquisition without any ECG/cardiac gating or synchronization that achieves the required image contrast for imaging perfusion defects. The invention also teaches an accelerated image reconstruction technique that is tailored to the data acquisition scheme and minimizes or eliminates dark-rim image artifacts. The invention further enables concurrent imaging of perfusion and myocardial wall motion (cardiac function), which can eliminate the need for separate assessment of cardiac function (hence shortening exam time), and/or provide complementary diagnostic information in CAD patients. In some embodiments, radial-geometry-based acquisition method and sampling method are applied to generate eight (8) real-time frames per second. No external ECG signal or other forms of cardiac synchronization is needed for this method.